ML20150F391
| ML20150F391 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 07/07/1988 |
| From: | Randazza J Maine Yankee |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GDW-88-179, IEB-88-004, IEB-88-4, MN-88-71, NUDOCS 8807180272 | |
| Download: ML20150F391 (10) | |
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-e MaineYankee RELIABLE ELECTRICITY FOR MAINE SINCE 1972 EDISON DRIVE. AUGUSTA MAINE 04330.(207) 623-3521 L-July 7,1988 MN-88-71 GDW-88-179 UNITED STATES NUCLEAR REGULATORY COMMISSION j
Attention: Document Control Desk Washington, D. C.
20555
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) i)SNRC Bulletin No. 88-04:
Potential Safety-Related Pump Loss Gentlemen:
Subject:
Response to NRC Bulletin No. 88-04 Reference (b) requested investigation and, as applicable, correction of two miniflow design concerns. Attachment A to this letter restates each requested action and provides Maine Yankee's response.
Based on our analysis, we conclude that the Maine Yankee plant design and operation and surveillance practices preclude problems with miniflow as identified in NRC Bulletin No. 88-04.
As stated in Attachment A, we will follow up with the pump suppliers as final confirmation of this conclusion and report results to you.
Very truly yours, John B. Randazza President JBR/bjp Attachments c:
Mr. Richard H. Wessman Mr. William T. Russell Mr. Cornelius F. Holden Mr. Patrick M.
Sears Mr. Clough Toppan STATE OF MAINE Then personally appeared before me, John B. Randazza, who being duly sworn did state that he is President of Maine Yankee Atomic Power Company, that he is duly authorized to execute and file the foregoing request in the name and on behalf of Maine Yankee Atomic Power Company, and that the statements therein are true to the best of his knowledge and belief.
LLNbb No uMc 8807180272 880707 J-DR ADOCK 05000309 py cw:Emost(Nm PNU AME 21.1994 fjll Ih t.
MaineYankee 1
l ATTACHMENT A Response to NRC Bulletin No. 88-04:
Potential Safety-Related Pump Loss (In the following, each Action requested by the Bulletin is restated, followed by Maine Yankee's response).
NRC Bulletin Item #1 Promptly determine whether or not its facility has any safety-related system with a pump and piping system configuration that does not preclude pump-to-pump interaction during miniflow operation and could therefore result in deadheading of one or more of the pumps.
Maine Yankee Resoonse Maine Yankee has four sets of pumps that may be required.for safe shutdown and accident mitigation and that have minimum recirculation systems.
-These are the:
1.
High Pressure Safety Injection Pumps (HPSI/P-14A,B S) 2.
Low Pressure Safety Injection Pumps-(LPSI/P-12A,B) 3.
Containment Spray Pumps (CS/P-61A,B S) 4.
Emergency Feedwater Pumps (EFH/P-25A,C)
NOTE:
The turbine driven Auxiliary Feedwater Pump (P-258) is not run simultaneously with the Emergency Feedwater Pumps nor required to mitigate a design base accident.
Therefore, it is not considered under this evaluation.
Maine Yankee's minimum recirculation (HR) systems do not deadhead pumps upstream of a common recirculation orifice, like the design discussed in tne Bulletin does. Our HR systems minimize the probability of deadheading the associated pumps.
A simp 1*fied diagram of the Maine Yankee HR designs and the Hestinghouse design is attached along with selected pump information (Attachment B).
NRC Bulletin Item #2 If the situation described in Item 1 exists, evaluate the system for flow l
division taking into consideration (a) the actual line and component l
resistances for the as-built configuration of the identified system; (b) l the head versus flow characteristics of the installed pumps, including l
actual test data for "strong" and "weak" pump flows; (c) the effect of l
test instrument error and reading error; and (d) the worst case allowances for deviation of pump test parameters as allowed by the American Society of Hechanical Engineers Boiler and Pressure Vessel Code (ASME Code)
Section XI, Paragraph IHP-3100.
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MaineYankee
- Maine Yankee Resoonse Maine Yankee. believes that our configuration will preclude pump-to-pump interaction during minimum flow operation and additional evaluation is not
. planned at this time.
NRC Bulletin Item #3 Evaluate the adequacy of the niinimum flow bypass lines for safety-related centrifugal pumps with respect to damage resulting from operation and.
testing in the minimum flow mode.
This evaluation.should include consideration of the effects of cumulative operating hours in the minimum flow mode over the lifetime of the plant and during the postulated accident scenario involving the largest time spent in this mode.
The evaluation should be based on best current estimates of potential pump damage from operation of the specific pump models involved, derived from pertinent test data and field experience on pump damage.
The evaluation should slso include verification from the pump suppliers that current miniflow rates (or any proposed modifications to miniflow systems) are sufficient to ensure that there will be no pump damage from low flow operation.
If the test data do not justify the existing capacity of the bypass lines (e.g., if the data do not come from flows comparable to the current capacity) or if the pump supplier does not verify the adequacy of the current miniflow capacity, the licensee should proviae a plan to obtain additional test data and/or modify the miniflow-capacity as needed.
Maine Yankee Resoonse The HPSI pumps are used for normal makeup to the Reactor Coolant System (RCS).
They are monitored by the plant computer and checked locally by plant personnel, at least 6 times a day.
They are also tested each month (except during shutdowns).
Pump temperatures, pressures, vibrations and inspections indicate that the pumps are in good operating condition.
If HR was inadequate, we would have seen the affects over the last 16 years and corrected the condition.
The LPSI, CS and EFH pumps have been tested every month (except during shutdowns) for the last 16 years.
They are run at minimum recirculation for approximately 15-30 minutes.
The pump vibrations, temperatures and other operating parameters indicate that MR capacities are acceptable.
Over the last 16 years of service, the total number of hours on MR has accumulated. However, 16 years of testing and preventative maintenance has also proven that the pumps are not being degraded by operation at MR.
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MaineYankee The Nuclear Plant Reliability Data System was checked to determine if other utilities had experienced flow induced failures of pumps with similar model numbers.
No failures were directly related to minimum
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recirculation.
Estimates are attached (Attachment C), which describe common scenarios and the times that pumps are at MR.
The estimates are based on plant and simulator experiences, but they will not provide accurate totals because our procedures and operational demands have varied over the last.16 years. However,,they do reflect current practices and provide insight as to the adequacy of our existing systems.
Maine Yankee will ask the pump suppliers to verify MR requirements by April 30, 1989. Maine Yankee plans to evaluate information from pump suppliers and notify the NRC of our findings, and any plans for additional testing or modificatioas by December 31, 1989.
((RC Bulletin Item #4 Within 60 days of receipt of this bulletin, provide a written response that (a) summarizes the problems and the systems affected, (b) identifies the short-term and long-term modifications to plant operating procedures or hardware that have been or are being implemented to ensure safe plant operations, (c) identifies an appropriate schedule for long-term resolution of this and/or other significant problems that-are identified as a result of this bulletin, and (d) provides justification for continued operation particularly with regard to General Design Criterion 35 of Appendix A to Title 10 of the Code of Federal Regulations (10 CFR 50),
"Emergency Core Cooling" and 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling System for Light Water Nuclear Power Reactors."
Maine Yankee Resoonse Maine Yankee's safeguards pumps do not share a common recirculation s
orifice and undesirable pump-to-pump interactions will not occur.
Therefore, we believe that the first concern raised by NRC Bulletin No.
88-04 does not apply to Maine Yankee, and no further action is planned.
Our minimum recirculation systems were not intended for continuous service, and they are not used for continuous service.
The second issue raised by this bulletin suggests that continuous operation at low flows may degrade some types of pumps. He recognize this concern but are also confident that our pumps will operate properly during transients and normal service. Our history and procedures indicate that undesirable shifts in previous trends are unlikely.
Maine Yankee plans to evaluate information from pump suppliers and notify the NRC of our findings, and any plans for additional testing or modifications by December 31, 1989.
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'MaineYankee
. NRC Bulletin Item #5 Within 30 days of completion of the long-term resolution actions, provide a written response describing the actions taken.
Maine Yankee Resoonse As stated in the response to Item 4 above, Maine Yankee will inform the NRC of additional findings and, if required, plans for additional testing 10 or modification.
Within 30 days of completing the long-term resolution
~
actions, Maine Yankee will provide a written response describing the
. actions taken.
NRC Bulletin Item #6 4
An_ evaluation of your actions in response to this bulletin should be documented and maintained at the plant site for a minimum of two (2) years. That evaluation should, as a minimum, address the piping system configuration in accordance with Item 1 above, each of the four factors discussed in Item 2, pertinent test data and field experience on minimum flow operation, and verification of the adequacy of current miniflow capacity by the pump manufacturer.
Maine Yankee Resoonse Maine Yankee will maintain appropriate documentation to comply with this requested action.
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MaineTankee ATTACHMENT B
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' Pump and Minimum Recirculation System Information Hich' Pressure Safety In_iection (HPSI)
Bingham - Horizontal, 9 stage, Centrifugal Rated Flow / Head 200 gpm @5.500 ft (TDH)
Shutoff Pressure 5,750 ft (TDH)
Minimum Flow 50 gpm Minimum Flow Orifice 12 stage Low Pressure Safety Injection (LPSI/RHR)
Bingham - Vertical, 2 stage, Centrifu;;al - 14 x 16188-VCR Rated Flow / Head 3,000 gpm/365 ft (TDH)
Shutoff Pressure 430 FT.(TDH)
Hinimum Flow 350 gpm Minimum Flow Orifice 1 stage 1 1/4 in dia Hin. Flow Disch. Pressures 180 to 184 psig (from tests)
Containment Sorav (CS)
Byron Jackson - Vertical, 2 stage, Co-Axial Turbine - 18 CKXH Rated Flow / Head 3,700 gpm/305 ft (TDH)
Shutoff Pressure 420 ft (TDH)
Minimum Flow 425 GPM Minimum Flow Orifice 1 stage 1 1/16 in dia Hin. Flow Disch. Pressure 192 to 195 psig (from tests)
Emeroency Feedwater (EfB1 Ingersoll-Rand - Horizontal, 8 stage, Centrifugal - 3HHTA - 8 Rated Flow / Head 525 gpm @l100 psig or 2,500 ft Shutoff Pressure 3.200 ft (TDH)
Minimum Flow by IR 20 gpm Minimum Flow Orifice by IR 6 stage 1/4" holes Minimum Flow Disch. Pressure 1,400 to 1,450 psig (from tests) i 0241L-RCC
SIMPLIFIED MINIMUM RECIRCULATION SYSTEMS WESTINGHOUSE DESIGN - LPSI/RHR m
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FROM:CEOG-88-299 MAINE YANKEE DESIGN - LPSI(RHR)/CS RAS CLOSES 6'm TK 4
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MaineYankee ATTACHMENT C Estimated Times at Minimum Flow HPST Degg
Normal Operation Reference Procedure 1-11-6.
Minimum Recirculation (MR). time is insignificant.
- Monthly Surveillance Tests Reference Procedure 3.1.2, 3.17.6.6 Tests are performed with the pumps in their normal charging mode and they are not run at MR.
- Loop Fill and Vent Reference Procedure 1-10-1 This operation may require up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> with 50 gpm HR plus 12-14 gpm of seal water.
This is a rough estimate because there are several evolutions that place the pump at MR, MR with seal water, and MR with seal water and 75-100 gpm make up.
- Refueling Surveillance Tests Reference Procedure 3.1.15.2 and 3.1.15.3 The tests do not place the pumps at MR.
Emergency Core Cooling Reference Procedure E-0, E-1, ES-1.1 One pump is normally charging and second pump starts on a SIAS.
The discharge valves shift within 13 seconds to establish HPSI and terminate charging.
- The worst case is a loop fill and vent which may place a pump at MR intermittently for several hours.
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LPSI-(RHR) Pumps' Ij '
- Normal Operation-(Residual Heat Removal)-
Reference Procedures 1-13-1 and-1-13 The pumps are not operated at minimum recirculation during RHR startup, operation or termination.
- Monthly Surveillances
.-Reference Procedure 3.1.2 and 3.17.6.6 The. pumps-are tested in the minimum recirculation mode for 15 to 30 minutes each.
- Refueling. Surveillance Tests Reference Procedure 3.1.15.2, 3.1.15.3 u.
The tests do not place the pumps at MR.
- Emergency Core Cooling
-Reference Procedure E-0, E-1, ES-1.1, ES-1.2, E-3 lBoth pumps start on a safety injection _ actuation signal (SIAS).
They operate on minimum recirculation until the RCS pressure drops to.190 psig,.or until they are secured by an operator.
- The worst case estimate is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at MR during a small' b'reak LOCA.~
C3 Pumos
- The containment spray pumps are only used during surveillance tests and emergency core cooling
- Monthly Surveillance Tes'ts Reference Procedure 3.1.2 and 3.17.6.6
.The'. pumps are tested in the MR mode for 15 to 30 minutes each.
- Refueling Surveillance Tests Reference Procedure 3.1.15.3 Some of the recirculation flow tests place the pumps at MR for brief periods.
- Emergency Core Cooling Reference Procedure E-1, E-3, ES-1.1, ES-1.2 The pumps start on a SIAS and run on recirculation until the
- ~
containment pressure exceeds 20 psig-or an operator secures the L
. pumps.
The maximum time on HR is estimated to be 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
- The worst case ' estimate is 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at MR during a small break LOCA.
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blaineYankee
'EFH Pumos
- Normal' Operation (Heatup, Cooldown.. Standby)
Reference Procedure 1-1, 1 The procedures do not preclude operation at MR. One-pump _could be on MR-for:Up to 30 minutes.
- Monthly Surveillances Reference Procedure.3.1.5 and 3.17.6.6
.The pumps are operated at MR for 15 to 30 minutes each.
- Post Trip Cooling
_ Reference Procedure E-0 and E-0.1 Pumps start on a _ low : team generator level (351.) and provide. full flow.
If the Feedwater (FH) pumps-are not~ operating,~ the EFH pumps are throttled back to approximately 200 gpm per generator but not less than 490 gpm-total flow to all three generators.
'If a FN. pump was in operation, the EFH pumps would provide 20 gpm ps.r generator plus 20 gpm MR for less than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
- Placing Steam Generators in Het Lay-up.
Reference Procedure 1-104-14.
The EFH pumps are not run on recirculation.
- Refueling Surveill_ance Tests-Referenco Procedure 3.1.22 The pumps may.be at MR for less than 30 minutes.
- The worst case estimate is 30 minutes of operation during surveillance tests.
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